Many people are familiar with insects laying eggs in dead or rotting meat or dead animal flesh. After the insects, notably flies, lay their eggs, the offspring go through several stages of development on the flesh before leaving. In the case of a criminal investigation, forensic investigators can use their knowledge of the insects lifecycle to estimate time of death. For an approximate estimate the investigator needs to ascertain the stage of the lifecycle the insect has reached and the time the eggs could have been laid.
In your class you will be having your students develop "traps" that can capture insects for identification. The traps are made of tin cans, a funnel, some pieces of wood, plastic bag, a can of cat food and some form of adhesive material like glue or tape. This diagram shows what the trap should look like after it has been put together. You will notice the food is at the bottom. The insects are attracted to the food. After eating or laying eggs, their natural behaviour is to fly upward. They fly through the funnel and become trapped in the bag. The traps will need to be placed somewhere where other animals can't reach the food. The trap should also be placed in a reasonably dry location.
Using the provided identification key, students should be able to determine the type(s) and number of insects they have caught. Students may need to use some magnifying device to see make an appropriate identification. Once identified the insects should be free-dried (by placing in the freezer for at least 48 hours and then packaged in a plastic bottle for delivery. You should be able to make one mail delivery at the end of the unit. All insects in a bottle should be of the same species and with name and number identified on the bottle. This information can then be sent to:
Forensic Science Insect Collection Project
c/o Dr
Gail Anderson
Cener for Pest Management
Department of Biological
Sciences
Simon Fraser University
Burnaby, B.C. Canada, V5A
1S6
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